Combustion of fuel, particularly carbonaceous materials such as fossil fuels and waste, results in flue gas streams that contain impurities, such as mercury (Hg), sulfur oxides (SOx), nitrogen oxides (NOx), and particulates, such as fly ash, which must be removed or reduced to a more acceptable level prior to releasing the flue gas stream to the environment. In response to regulations in place in many jurisdictions, numerous processes and apparatuses have been developed to remove or reduce the levels of impurities and particulates in such flue gas streams.
The typical method of reducing flue gas particulates, Hg, NOx, and SOx impurities from steam generating boilers powered by fuel combustion is by the use of flue gas stream treatment equipment. Such equipment includes, but is not limited to, electrostatic precipitators (ESP), fabric filter bag houses, catalytic systems, wet flue gas desulfurization (WFGD) systems and/or dry flue gas desulfurization (DFGD) systems.
In some flue gas stream processing systems, removal of acidic components, such as SOx, is facilitated through the use of a DFGD system, wherein a reagent slurry or solution contacts the flue gas stream and reacts with the SOx present therein. Current DFGD systems typically utilize spray dryer absorbers (SDAs) having an atomizer system that disperses the reagent slurry, typically in combination with a dilution liquid.
Current DFGD systems are slow to respond to SOx concentration swings in the flue gas stream. Accordingly, what is needed is a system and process that responds to SOx concentration swings in a timely manner while maintaining the SOx emission levels from a stack at or below a desired threshold established for the system.